1. Field of the Invention
The invention relates to frequency generation of synthesis using phase-locked loop circuitry.
2. Description of the Prior Art
Phase and frequency control by phase-locked loop techniques is known per se. Such regulating circuits are exhaustively described in the relevant literature, e.g. the text by R. Best "Theorie und Anwendungen des Phase-Locked Loops", Aarau/Switzerland, 1976. In the hitherto conventional types of frequency/phase-locked loops, the frequency-controlled generator is a voltage-controlled oscillator (VCO) while the phase comparator may either have an analog-linear characteristic, or may include digital hardware. The quite extensive patent literature relating to this art and also in other relevant literature reveals that in conventional frequency/phase-locked loops the frequency-controlled generator is invariably an analog voltage-controlled generator. Although satisfactory performance from analog VCO circuits can be obtained, there is always need for simple, low-cost, high performance alternatives. The manner in which the invention addresses this need will be evident as this description proceeds.